React is usually pretty fast, but it’s easy to make small mistakes that lead to performance issues. Slow component mounts, deep component trees, and unnecessary render cycles can quickly add up to an app that feels slow. Luckily there are lots of tools, some even built in to React, that help with diagnosing performance issues. In this post I’ll highlight tools and techniques for making React apps fast. Each section also has an interactive, and (hopefully) fun demo!